The relationship between auxin concentration, auxin protection and auxin destruction in crown gall cells cultured in vitro

Auxin content and IAA-protector activities in cultured crowngall cells were measured at various points of growth in subculture.A coincidence was observed between the change in IAA contentand IAA-protector activities in the cells: high auxin contentswith high IAA-protector activities were obtained at the latelog stage, and low auxin contents with low IAA-protector activitiesat the middle log and at the stationary stages. On the otherhand, IAA-destruction activities in the cells increased slightlythroughout the growth period of the cells. Addition of 2,4-Dto the culture depressed the auxin content and accelerated theIAA-destruction activity in the cells. These results suggestthe existence of a mechanism of negative-feed-back control ofauxin in crown gall cells. (Received May 1, 1978; )